Calculating instrument with optical



March 4, 1952 Filed April 5 1951 E. K. M CALCULATING INST PROJECTIONSYSTE ETTLER ET AL RUMENT WITH OPTICAL M FOR MAGNIFICATION 3Sheets-Sheet l March 4, 1952 E. K. METTLER ET AL 2,588,269 CALCULATINGINSTRUMENT WITH OPTICAL PROJECTION SYSTEM FOR MAGNIFICATION Filed April5 1951 3 Sheets-Sheet 2 March 4, 1952 E. K. METTLER ET AL 2,588,269

CALCULATING INSTRUMENT WITH OPTICAL PROJECTION SYSTEM FOR MAGNIFICATIONFiled April 5, 1951 3 Sheets-Sheet 3 IIIIIIIIIA Patented Mar. 4, 1952CALCULATING INSTRUMENT WITH OPTICAL PROJECTION SYSTEM FOR MAGNIFICA-TION' Erhard .Karl 'Mettler, Zollikon, Zurich, and JohannMeier,"Kusnacht, Zurich, Switzerland Application April;5, 1951,Serial'No.'219,364 In Switzerland July 19,1950.

8'Claims.

.This invention relates to a calculating instrument having-a pluralityof rotatable scale .carriers and having lined'scales according'to theprinciple of the slide rule.

Objects of the invention are to provide acalculating instrument of thetypestated in which the casing of the instrument encloses rotatablescale carriers which eachhaveone or more fine scales, and anilluminating device andoan enlarging optical system by means of which asmall sectionoi the fine. scales is depicted in enlarged scale on aprojection screen provided on the casing, each of said carriershavingfine scales being mechanically coupled by means of a toothed gearingwith a further rotatable scale carrierion whichare locatedmutuallycorresponding coarse scales which over alarge section of'their lengthare made .directly visible, all the fine scale carriers beingeachdisposed co-axially and allthe coarse scale carriers being each disposedco-axially. Objects are to provide in a calculating instrument of thetype indicated, fine scale carriers'fittedin the lower part of thecasing, their axis of rotation standingperpendicular to the base planeof the instrument, the axis of rotation of the coarse scalecarriers'running parallel to the base'plane of the instrument, a windowbeing providedin'thatop part of the 'front wall of the casing forreading the sections of the fine scales depictedmagnified on theprojection screen, and a further window being situatedbelow'the firstmentioned window through which further window the sections visible atanytime of the corresponding coarse scales can be read. Objects aretoprovide; in-a calculating instrument of thetype stated, acasingenclosing rotatable scale carriers which each have one 'or morefine scales, anillumin'ating device and a magnifying'optical'systembymeans of which a small section of said fine scales is depicted inenlarged scale on a projectionscreen provided insa'id'c'asing, eachofthe fine scale carriers being mechanically. coupled with a fLuther-rotatable scale carrieronwhich are located mutually correspondingcoarse scales which overalargasectionof their length are madedirectlyvisible; and an adjusting device operable from outside thecasing of the instrument; by means of which each of the pairs consistingofiafine'scale-carrierand the corresponding coarse scale'carried mechanicallycoupled with it can be rotated individually orsimultaneouslywith-each othenatwill. Yet another object of the inventionis'a' calculating instrument of the: type-stated; wherein the-fine scalesections of each fine scale carrier depicted on the projection screen inenIa-rgedEscaIe 'and the directly readable coarse scale sections of theassociated coarse scale carrier appear by means of colour filters in thesame colouring, the scales of each pairing of fine scale and coarsescale carriers having their own colour, and the various visible scalesections being indicated with the mathematical functions represented bythem.

These and other objects and the advantages of the invention will beapparent from the following specification when taken with theaccompanying drawing in which:

Fig. 1 isa longitudinal section of thecalculating instrument embodyingthe invention;

Fig. 2 is a plan view corresponding to Fig. l with the casing removed;

Fig. .3 is across section on the line 3-3 of Figs. 1 and 2; and

Fig. 4 is a cross section on the line '4-4 of .Figs. 1 and 2.

In the drawing, the reference numerals 3 identify the base of theinstrument on which the casing 4 is supported in removable manner. Theflange 5 of a partially cylindrical and partially conical slidingbearing '6 is screwed on to the middle portion of the base 3. On thishearing 6 a scale carrier 1 is rotatably mounted. The scale carrier 1possesses a tubular and conical taper '8 which extends upwards in anaxial direction, and at the outer rim of said scale carrier 1 atransparent annular glass disc 9 is cemented on. A further rotatablescale carrier I0 with an'annular glass disc H is seated on a cylindricalconical sliding bearing l2, the-"plate-shaped foot part l3 of which isscrewed on to the columns l4, l5, l6, H as is clearly shown in Fig. 2.

Thecolumns M to I! are preferably cast integral with'the base plate 3.Further, the sliding bearings 6 and I2 are so secured on'the base'3 thatthe wheel-shaped scale carriers 1 and ID are exactly co-axial, beingspaced from one another in the axial direction. On each of the planedisc surfaces-of the transparent glass rings Band II, fine scalesextending concentrically toeach other are fitted with such finegraduation and lettering that they cannot be-read directly with thenaked eye. These lined scales which are located at a small radialspacing from each other, lie on the rings Sand H roughly at the place ofthe circular line 18 indicated in Fig. 2. By means of an illuminatingdevice and an enlarging optical'system at any time a small section ofthese fine scales are projected with large magnification on to-aprojection screen l9, which is preferably a semi-transparent'opaquedisc. Theilluminating devicean'd the-magnifying optical system canconsist of two equal parts, each of which is associated with one of thetwo fine scale carriers 1 and It). For the enlarged reproduction of thefine scale sections located on the upper scale carrier II], a ray oflight proceeding from a lamp 25 first passes through a lens system .2 I,22 (Fig. 3) and is directed by means of a mirror 23 on to the glass discThe light rays proceeding from the illuminated fine scale sections passthrough the projection lens 24 and are thrown to the '4 left by a prism25 (Fig. 3) on to a mirror 26. From the mirror 26 (Figs. 1 and 2) theyare refiected Via the further mirrors 2? and 28 on the opaque disc l9,as illustrated by the ray course 29 entered in dotted lines. the lightemitted by the lamp 3|] is collected by lens system 3|, 32 and thrown bya mirror 33 on to the glass disc 9 (Fig. 3) belonging to the lower scalecarrier 1. The light emitted from the illuminated scale parts on theglass disc 9 passes through the projection lens 34 and is deflected tothe right by a prism 35 so that it falls onto a mirror 36. From themirror 36 (Figs. 2 and 3) the light ray is thrown in correspondingmanner by way of further mirrors 31 and 38 onto the 42 located at thefront and the parts secured to n them are consequently not indicated.The lamp 30 and the retaining means for one condenser lens 3| (Fig. 3)can be erected directly on the base 3. As can be seen further from thedotted ray courses 29 and 39 (Fig. 2), the optically enlarged sectionsof the fine scales are depicted side by side along the length of theline-shaped reading mark 43 made on the opaque disc Hi. If from thisposition one or both of the fine scale carriers l and I are slowlyrotated in a clock-wise direction, then, obviously taking into accountthe optical inversion by the projection lenses 24 and 34, the enlargedsections of the fine scales make their way on the projection screen inFig. 1 from the bottom to the top beyond the reading mark 43.

- With each of the two fine scale carriers 1 and H) is associated acoarse scale carrier 44 and 45. The coarse scale carriers 44 and 45 arerollers which are rotatable in a horizontal direction and which extendparallel to the reading mark 43 present on the opaque disc l9 and areeach separately rotatable side by side on the shaft 46. The shaft 46 issecured in projecting arms of two In a similar manner arrangement astheir associated corresponding fine scale sections reproduced on theopaque disc l9. If, for instance, the glass disc I of the upper scalecarrier ||l possesses, seen radially from the inside to the outside inturn the fine scales of the functions c log x, :8 x, then enlargedsections of these functions appear on the opaque disc |9 in the sequenceindicated, beginning on the side of the strut 48 (Fig. 2) and advancingtowards the middle of the opaque disc. In this same sequence thecorresponding coarse scales are arranged on the roller associated withthe fine scale carrier H), as indicated by the lettered plate 53 (Fig.2). If furthermore the functions at, sin A (large angle), sin a (small.angle), tg A (large angle), tg a (small angle),

K (usual constants) are to be placed on the roller 44 in the sequenceindicated, then in similar manner the fine scales of the said functionsmust be placed in this sequence radially from the outside to the insideon the glass disc 9 of the associated lower fine scale carrier 1.

As can be seen from Fig. l, the lettered plate 53 is preferably disposedbetween the two win dows 5| and 52; in Fig. 2 the plate 53 has only beendrawn next to the rollers 44 and 45 for reasons of clearer graphicalrepresentation.

For facilitating the reading of the various coarse and fine sections ofthe scales the coarse scales present on the roller 45 and thecorresponding fine scale sections (Figs. 1 and 2) visible through thewindow 5| above the roller 45 can be made distinguishable for instanceby a red colouring and the coarse scales present on the roller 44 andthe corresponding fine scale sections located above the roller 44 andvisible through the window 5| can be made distinguishable for instanceby a green colouring. For this purpose, it is advantageous to fit infront of the lens 2| (Fig. 3) a colour filter 54 permitting the passageof red light, and in front of the lens 3| a colour filter 55 permittingthe passage of green light. Using such colour filters 54 and 55 has thefurther advantage that the lenses 2|, 22, 24 and 3|, 32, 34 do not haveto be achromatic lenses, whereby in particular shorter focal lengths canbe obtained with the projection lenses 24 and 34 and consequently higherenlargements with given image spacing.

The two rollers 44 and 45 are each mechanically coupled with the finescale carriers 1 and H] by way of a toothed gearing. The side of theroller 44 facing the supporting strut 41 carries a toothed wheel 56 inmesh with a toothed wheel supporting struts 41 and 48 (Figs. 1' and 2)which at the same time are used for holding the opaque disc l9 and arescrewed on the base 3 by means of a common base plate 49. Between theprojecting arms of the supporting struts 4'! and 48 a thread-likereading mark 5!! is stretched parallel to the shaft 46 and obliquelythereabove (Fig. 1) directly above the surface of the rollers 44 and 45.Below a window 5| recessed in the casing 4 (Fig. 1) for reading the finescale sections which are visibly enlarged on the screen l9,

there is made a further window 52 through which under the reading mark50 large sections of the 58 disposed on the vertical shaft 51. On theshaft 51 is a further toothed wheel 59 which is in mesh with a toothedwheel 60 on a horizontal shaft 6| (Figs. 1 and 2). Finally, a furthertoothed wheel 62 secured on the shaft 6| engages in a toothed rim 63disposed on the lower fine scale carrier 1 (Fig. 1). Similarly, the sideof the roller 45 facing the supporting strut 48 has a toothed wheel 64(Fig.

, 2), which, by way of a toothed wheel 65, a shaft 66(Figs. l and 2),toothed wheels 61 and 68, a shaft 69 and a toothed wheel 15, ismechanically coupled with the toothed rim N (Fig. 1) seated on the upperfine scale carrier II). The said two toothed gearings are such thatmanifestly on a rotation of the fine scale carriers I and I6 in aclock-wise direction (Fig. 2) the two rollers 44 and 45 in theillustration according to Fig. I are also rotated in a clock-wisedirection. Con:

' sequently if one observes through the. two windows 5| and 52 (Fig. 1)the associated sections ofacoarse scale. and the corresponding finescale,

these move; onrotationof the scale carriers. 1, 44 or 18, 45 in the samedirection beyond the reading marks43 and 58. The :operationof theinstrument. in practice thereby made much easier. Further, because onthe scale carriers 1, 44 and I0, 45 the beginning. of the. scale and theend of the scale of the functions employed coincide, for :1), r and forintegral positive powers of :n, with circular construction of the scalegraduation, the transmission ratio of the toothed gearings 'de-.scribedabove is preferably made. 1:1. Acomplete. revolution of the finescale carriers l on) then likewise-causes a full revolution of thecorre-. sponding coarse scale carriers 44 or 45.

Finally, Fig. 4 shows in partial sectionalan adjusting device which canbe operated from out-.

side the casing4 and by means of which each of the pairs I, 44 or 10, 45consistingof. a fine scale carrier and its associated coarse scale.carrier, can=be each rotated at will individually or simultaneously,tobring the desired scale parts over the corresponding reading marks-43 or50 (Figs. 1 and 2). Here, in Fig. 4, as in Fig. 3, the casing 4, whichcan be supported on the shoulder 12 of the :base 3 has not beenshown forreasonsof clarity. In-the form of construction shownthe adjusting device.consistsof a drive withcoarse.

and finesetting for the scale carriers .1, 44, a drive withcoarse andfine setting for the scale carriers l8, 45', and a coupling device bywhich the scale carriers 1, 44 and i8, 45 can be jointly rotated.

For the drive of the scale carriers 1, 44 a shaft 13 is provided whichis mounted so as to be axially displaceable, and has a part projectingbeyond the casing wall, said part carrying the actuating knob 14. Theshaft 13 carries a toothed wheel 75 forefiecting thecoarse setting and.a'small friction disc 16 for the fine setting. Now if the actuatingknob 14 is pressed to the left (Fig. 4)., the toothed wheel 15 comesinto engagement .with the toothed rim 63 and the scale carriers 1, 44are coarsely set by rotating the knob 14. For actuating the finesetting,1the knob 14 ispushed to the right, so that the friction disc 16bearson thelower conical surface 11 of thefine scale carrier I asalreadyindicated in the drawing. By rotating the, knob 14 the fine scalecarrierv 1 can be finely set without any backlash; the roller. 44obviously also makesvv the fine movementin association withthe scalecarrier-Lin as far. as. the said motionis not located within the play ofthe. toothed gearing shown in Figs. 1 and 2.

The. drive of the scale carriers I0, .45 is effected in'similar mannerby means of the knob 18, the shaft 19, the friction disc 88 and thetoothed wheel 8|. The shaft 19 isylikewise axially displaceable, inorder to make possible coarse and fine setting,- and the scale carrierID has an appropriateconical face 82. In'Fig. 4, the shaft 19 is shownin the nonoperative position in which neitherthe fine settingwith thefriction disc 80 nor the coarse setting with the toothed wheel 8| isengaged. With the shafts 13 and 19, this nonoperative positioncanbe-fixed so that it. can be felt by means of grooves (not shown).

The coupling device uses a spring disc 83 (Fig. 2). provided withrecesses, which is screwed firstly to the scale carrier 18 and secondlyto a hollow cone 84 (Figs. 1 and 4). In the hollow cone 84 the .upperpart of a member 85 is rotatably mounted on a ball bearing, the lowerpart of the member 85 engages in a spring loaded sleeve 86., Asmovableeccentric slide valve 181, is -fiexibly'connected to the lower partofthespring 88. In the highest. .eccentric position shown. in. Fig. lthe spring encased in the spring sleeve .86.

is relaxed and the spring disc 83 draws the member 85 and the cone 84upwards. The coupling between the scale carriers 1, 44 on the one handand i0, 45 on the other hand is thus released;

consequently each of the pairs 1, 44 and I0, 45.

can be set and rotated independently of the other. pair.

If, for instance for performing multiplications or divisions, the pairsof scale carriers 7, 44 and- Ill, 45 are to be rotated with eachother,-then;

the knob is turned through half a revolution so that'the eccentric disc88 changes over from.

the highest position shown in Fig. 1 into the lowest position shown inFig. 4. The spring present inthe spring sleeve 88 is somewhatcompressed,

overcomes the action of the spring disc 83 and draws the member 85 andthe cone 84 downwards until the cone 84 is pressed onto the hollowcounter-cone 8 of the scale-carrier 1. The pairs-of scale carriers 1, 44and I0, 45'are thus coupled with each other. In Fig. 4, the scalecarrier 10 is rotated through 90 as compared with the illustration inFigs. 1 and 2 in order to illustrate betterthe downward deflection ofthe spring disc 83. Now in order to rotate the pairs 1, 44 and I0, 45 atthe same time one of the two shafts 13 or "ZS is brought into thenonoperative position (Fig.

4) and the coarse or fine adjustment as desired by means of the othershaft.

All parts of decisive importance for the accuracy of the instrument areevidently disposed within the casing 4. In particular the entire opticalsystem and the fine scales on the glass discs 9 and H are fully enclosedfrom external effects, and in particular are protected against iseffected direct handling and against dust. Soiling of the.-

fine scales and of the optical equipment isthus. not possible in normaluse of the instrument. Scale parts sliding upon each other are avoidedby the axial distancing of the scale carriers 1: and 18 so that wear ofany kind on the fine scales does not occur. The accuracy and fineness ofgraduation of the fine. scales can for these rea. sons be carried veryhigh. It is, for instance, possible to carry out exactly the division ofthe normal x-scale even at the end thereof (with. number values between9,000 and 10,000) to five figures, so that with an optical magnificationof about 30 to 60 reading can be carried out exactly to four figures andthe fifth figure can .still beestimated. The equivalentv scale length ofthe magnified fine scales is thus over twenty metres, while the spacingsbetween successive graduation lines on-the glass discs 9 and H can be ofthe order of one hundredth of a millimetre. On numerical calculationwith the instrument, one; thus has practically the same accuracy as oncalculating with the usual five figure logarithm tables but with thedifference that the amount of time required for a calculating operationis quite substantially less. I

The coarse scales on the rollers 44 and 45 permit a goodgeneral view oflarge sections of the scales and are particularly convenient in order tobe-able to set the desired numerical value;quickly.;

The 80*" The accuracy of thecoarse scales is approxi-' mately that of anormal pocket slide rule, since a reading accuracy to two or threefigures is sufficie'iit'. The coarse scales can therefore also be usedfor the rapid execution of rough estimating and checking calculations;because when the coarsescales are used alone, fine setting thereof isnot-necessary. Here the described roller-shape construction of thecoarse scale carriers makes it possible to dispose a large number ofdifierent scalesside by side in the same clear manner.

The simultaneous employment of coarse and fine scales further makes itpossible on reading a value, to read the first two to three figures fromthe coarse scales and only to take the last two to threei figuresthereof from the optically magnified 'fine scales. The numberings on thefine scale-lgraduations therefore do not need to contain-the first twofigures, whereby it becomes possiblelgto move adjoining fine scalescloser to each other and to accommodate a greater number of scales in agiven place. In the drawings (Fig. 2) only'six scales per scale carrierare indicated, but considerably more scales can be arranged withoutincreasing the dimensions of the instrument. The instrument can thenserve not only for exact calculating but can also replace the tables ofmathematical functions (trigonometrical and so on) which are otherwisenecessary from time to time.

The invention is not limited to the particular embodiment herein shownand described. It may be advisable, for instance, to provide metallicshields inside the casing to. protect the fine scale carriers againstheat emitted by the electric lamps 20 and 39 (Figs. 1 and 2). This andother modifications which may occur to those familiar with, the art fallwithin the spirit and scope of the invention as set forth in thefollowing claims.

We claim:

1. A calculating instrument having a plurality of rotatable scalecarriers, each of the scale carriershaving lined scales according to theprinciple of the slide rule, the casing of the instrument enclosingrotatable scale carriers which each" have one or more fine scales, andan illuminating device and a magnifying optical system by means of whicha small section of said fine scales is depicted in enlarged scale on aprojection screen provided on said casing, each of said fine scalecarriers being mechanically coupled by means of a toothed gearing with afurther rotatable scale carrier on which are located mutuallycorresponding coarse scales which over a large section of their lengthare made directly visible,

all the fine scale carriers being each disposed coaxially and all thecoarse scale carriers beir'ig each disposed co-axially.

2. The invention as recited in claim 1, wherein the co-axially disposedfine scale carriers are circular'discs on the surface of which the finescales are located and which discs are spaced from each other in anaxial direction, and wherein the co-axially disposed coarse scalecarriers are -rollers disposed side by side in an axial direcof thecasing, their axis of rotation standin perpendicular to the'base planeof the instrument, theaxis of rotation of the coarse scale carriersbeing disposed parallel to the base plane of the instrument, a windowbeing provided in the top part of the front wall of the casing forreading the sections of the fine scales depicted magnified on theprojection screen fitted behind said window, and a further Window beingsituated below the first mentioned window through which further windowthe sections visible of the corresponding coarse scale can be read.

4. The invention as recited in claim 2, wherein a line-shaped readingmark placed above the rollers runs parallel to the axial direction ofthe rollers and the axial direction of the rollers runs parallel to thereading mark visible on the proeach have one or more fine scales, anilluminating device and a magnifying optical system by means of which asmall section of said fine scales is depicted in enlarged scale on aprojection screen provided in said casing, each of, said fine scalecarriers being mechanically coupled with a further rotatable scalecarrier on which are located mutually corresponding coarse scales whichover a large section of their length are made directly visible, and anadjusting device operable from outside the casing of the instru ment, bymeans of which each of the pairs consisting of a fine scale carrier andthe corresponding coarse scale carrier mechanically coupled with it canbe rotated individually or simultaneously with each other at will.

6. The invention as recited in claim 5,'wherein inside the casing, thereis associated with each fine scale carrier its own projection lens, anda plurality of mirrors is fitted with which the enlarged sections of allthe fine scales are depicted side by side on the projection screen inthe direction of a straight line reading mark visible on said projectionscreen.

7. A calculating instrument having a plurality of rotatable scalecarriers, each of which having lined scales according to the principleof the slide rule, the casing of the instrument enclosing two rotatablescale carriers which each have a plurality of fine scales, a smallsection of said fine scales being depicted by means of an'illuminatingdevice and a magnifying optical system in enlarged scale on a projectionscreen, each of said two fine scale carriers being mechanically coupledwith a further rotatable scale carrier on which are located mutuallycorresponding coarse scales which over a large section of their lengthare made directly visible, an adjusting device operable from outside thecasing of the instrument by means of which the one pair consisting of afine scale carrier and the corresponding coarse scale carriermechanically coupled with it can be rotated, an adjusting deviceoperable from outside the casing of the instrument by means of which theother pair consisting of a fine scale carrier and the correspondingcoarse scale carrier mechanically coupled with it can be rotated, and acoupling device operable from outside the casing of the instrument inthe released position of which said two pairs of scale carriers can berotated individually 10 and in the closed position of which said twoREFERENCES CITED pairs of scale carriers can be rotated simultane- Thefollowing references are of record in the ously by means of said twoadjusting devices. me of this patent;

8. The invention as recited in claim 7, wherein each of said twoadjusting devices comprises 5 UNITED STATES PATENTS manually opei'ablemeans for the coarse setting Number Name Date of the scale carriers andmanually operable 922,465 Fenn May 25, 1909 means for the fine settingof the scale carriers. 2,177,176 Gilmore Oct. 24, 1939 2,356,274 RogerAug. 24, 1944 ERHARD KARL ME'I'I ER- in 2,365,613 Wibmer et a1. Dec. 19,1944 JOHANN MEIER. 2,552,272 Fultz May 8, 1951

